![]() ![]() ![]() The anemometer measures wind speed by measuring how fast the wind makes a fan blade turn. The speed of the wind will be measured using a handheld device called an anemometer. In this science fair project, you will measure how wind speed affects the rate of cooling of an object. What happens if you spray the cup of hot coffee with a mist of water while you are blowing on it with a fan? It is then being cooled by both convective and evaporative means thus, it will cool faster than the dry cup and will also cool to a temperature a little below room temperature. If you blow on it with a fan, it will cool faster, but it will only cool to room temperature and no further. For example, if you put a cup of hot coffee on a table, it will eventually cool to room temperature. In convective cooling, the object can only be cooled to the temperature of its surroundings. Both kinds of cooling occur on human (and animal) skin that is exposed to cold wind.įor an inanimate object that has a dry surface, only convective cooling occurs. As the moisture evaporates, it causes the surface to cool. Another way it cools is by evaporating the moisture on your skin. The first way is by simply blowing away the warm air that is next to your skin and replacing it with cold air. There are two ways that the wind cools things off. If it is minus 25☏ and the wind is blowing at 40 mph (this is in the purple part of the chart), you could get frostbite in as little as 5 minutes!įigure 1. If you are outside when the temperature is 0☏ and the wind is blowing at 30 miles per hour (mph), you could develop frostbite within 30 minutes on exposed parts of your body (usually your fingers and face). As it gets colder, the danger of frostbite increases. ![]() On the left side of the chart, the temperatures are relatively high, meaning there is no danger of frostbite (light blue). The chart in Figure 1, below, shows how wind speed affects the time it takes to develop frostbite at various temperatures. Windchill charts are useful to help predict when a person is most in danger of frostbite, which damages skin and other tissues due to extreme cold. As wind increases, heat is carried away from the body at a faster rate, driving down both skin temperature (which can cause frostbite) and eventually the internal body temperature (which, in extreme cases, can lead to death). When humidity is high, this evaporation reduces resulting in 'feels like' temperatures that appear warmer than the actual air temperature.The windchill factor describes what happens to an object (like your body) when it is cold and windy outside. When a human perspires, the water in the sweat evaporates leading to the cooling of the body as the heat is carried away. When the wind speed is low in periods of high temperatures, the 'feels like' temperatures become more impacted by the humidity level. If it is windy, the wind will take the boundary layer away and the skin temperature will drop making us feel colder. On a calm day, our bodies insulate us with a boundary layer which warms the air closest to the skin. An example of this is in winter when winds blowing to the UK from a north- easterly direction make the 'feels like' temperatures colder than the actual air temperature. 'Feels like' temperatures throughout the year are particularly influenced by wind. This has the effect of moving heat away from the body and making the surrounding air feel colder than it actually is. The 'feels like' temperature is especially important on windy days due to the effect of wind on the evaporation speed of moisture from skin, the stronger the wind, the faster the cooling of the skin.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |